New α-ditetralonyl glucoside from the green walnut husk of Juglans mandshurica

Article abstract of DOI:10.1080/14786419.2019.1608538

One new α-ditetralonyl glucoside (1), was isolated from the green walnut husk of Juglans mandshurica (Juglandaceae), together with twelve known compounds (2–13). The structure of the new compound was determined as (2R,4S,10S,12S)-2-[7-(12,13,16-trihydroxy-α-tetralonyl-13-O-β-D-glucopyranoside)]- 4,8-dihydroxy-α-tetralone-4-O-β-D-glucopyranoside (1), on the basis of detailed spectroscopic analyses, and acidic hydrolysis. Compounds 6, 7 and 11 were isolated from the genus Juglans for the first time. Compound 1–13 showed weak cytotoxic against A549 and HeLa cell lines.

Full text of DOI:10.1080/14786419.2019.1608538

Natural Product Research
Formerly Natural Product Letters
ISSN: 1478-6419 (Print) 1478-6427 (Online) Journal homepage: https://www.tandfonline.com/loi/gnpl20
New α-ditetralonyl glucoside from the green
walnut husk of Juglans mandshurica
An-Dong Wang, Xin-Yu Xie, Wei-Ming Zeng, Jian-Yu Liu & Yong-Nan Xu
To cite this article: An-Dong Wang, Xin-Yu Xie, Wei-Ming Zeng, Jian-Yu Liu & Yong-Nan Xu
(2019): New α-ditetralonyl glucoside from the green walnut husk of Juglansꢀmandshurica, Natural
Product Research, DOI: 10.1080/14786419.2019.1608538
To link to this article: https://doi.org/10.1080/14786419.2019.1608538
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NATURAL PRODUCT RESEARCH
https://doi.org/10.1080/14786419.2019.1608538
New a-ditetralonyl glucoside from the green walnut husk
of Juglans mandshurica
An-Dong Wanga,b
Yong-Nan Xub,c
, Xin-Yu Xieb,c , Wei-Ming Zengb,c, Jian-Yu Liub,c
and
ꢀ
ꢀ
aSchool of Traditional Chinese Medicine, Shenyang Pharmaceutical University, Shenyang, China;
bKey Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang
c
Pharmaceutical University, Shenyang, China; School of Pharmaceutical Engineering, Shenyang
Pharmaceutical University, Shenyang, China
ABSTRACT
ARTICLE HISTORY
Received 13 November 2018
Accepted 7 April 2019
One new a-ditetralonyl glucoside (1), was isolated from the green
walnut husk of Juglans mandshurica (Juglandaceae), together with
twelve known compounds (2–13). The structure of the new
compound was determined as (2R,4S,10S,12S)-2-[7-(12,13,16-trihy-
droxy-a-tetralonyl-13-O-b-D-glucopyranoside)]- 4,8-dihydroxy-a-tet-
ralone-4-O-b-D-glucopyranoside (1), on the basis of detailed
spectroscopic analyses, and acidic hydrolysis. Compounds 6, 7
and 11 were isolated from the genus Juglans for the first time.
Compound 1–13 showed weak cytotoxic against A549 and HeLa
cell lines.
KEYWORDS
Juglans mandshurica;
Juglandaceae; a-ditetralonyl
glucoside; cytotoxic activity
1. Introduction
The green walnut husk of Juglans mandshurica Maxim. (Juglandaceae), commonly
called Qinglongyi, has been used as a traditional medicine for treatment of cancer
and dermatosis in China (Park et al. 2017). It has been reported that J. mandshurica is
rich in naphthoquinones (Chen et al. 2015; Guo et al. 2015; Jin et al. 2016),
CONTACT Jian-Yu Liu
burningice@126.com; Yong-Nan Xu
ynxu@syphu.edu.cn
ꢀ
These authors contributed equally to this work and shared first authorship.
Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2019.1608538.
ß 2019 Informa UK Limited, trading as Taylor & Francis Group

2
A.-D. WANG ET AL.
Figure 1. The structure of compounds from the green walnut husks of J. mandshurica.
diarylheptanoids (Jin et al. 2015; Li et al. 2017) and flavonoids (also their glycosides)
(Wang et al. 2017; Xu and Bao 2014). As a continuation of our phytochemical investi-
gations, one new a-ditetralonyl glucoside (1) and twelve known compounds 2–13
(Figure 1) were isolated from the n-butanol solvent fraction of the green walnut husk
of J. mandshurica. Herein, we report the isolation, structural elucidation and cytotoxic
activity of the compounds.
2. Results and discussion
The 70% ethanol extract of the dried green walnut husk of J. mandshurica was sub-
jected to multiple chromatographic steps over silica gel, Sephadex LH-20 and recycling
preparation HPLC. Thirteen compounds were obtained, including one new
compound, (2R,4S,10S,12S)-2-[7-(12,13,16-trihydroxy-a-tetralonyl-13-O-b-D-glucopyrano-
side)]-4,8-dihydroxy-a-tetralone-4-O-b-D-glucopyranoside (1) and 12 known com-
pounds, irisfloretin (2) (Liu et al. 2011), puerarin (3) (nakamura et al. 2011), irigenin (4)
(Ibrahim et al. 2012), 4,5-dihydroblumenol (5) (Xiong et al. 2017), (Z)-6,7-epoxyligusti-
lide (6) (grech et al. 1994), 40-O-methylnyasol (7) (Tao et al. 2011), 4-hydroxybenzalde-
hyde (8) (Hsu et al. 2009), dibutylphthalate (9) (Wang et al. 2012), 2-[4-(3-
hydroxypropyl)-2-methoxyphenoxy]-propane-1,3-diol (10) (Zhao et al. 2017), tetradeca-
5,8-dienoic acid (11) (Alamsjah et al. 2007), linolenic acid (12) (Lee 2010), porrigenic
acid (13) (Hasegawa et al. 2007). The structures of 1-13 (Figure 1) were identified by
physical data analyses, including 1 D and 2 D NMR, and HRESIMS. The sugar residues
were identified by GC analyses after hydrolysis.
Compound 1 was obtained as a white amorphous powder. The molecular formula of
C32H28O17 was determined on the basis of the HR-ESI-MS (m/z 735.1998,
[M þ Na þ H2O]þ). Acidic hydrolysis of 1 gave D-glucose as the monosaccharide residue.
1
The H NMR and 13C NMR data of 1 exhibited the signals arising from two CO group at
dC 206.4(C-9), 201.0(C-1), one benzene ring at dH 7.50 (1H, d, J ¼ 7.7 Hz, H-7), 7.31 (1H, d,
J ¼ 7.9 Hz, H-6), 7.12 (1H, d, J ¼ 7.7 Hz, H-5), the other benzene ring at dH 7.55 (1H, d,
J ¼ 9.1 Hz, H-14), 6.89 (1H, d, J ¼ 9.1 Hz, H-15), b-glucopyranosyl moiety [anomeric H-

NATURAL PRODUCT RESEARCH
3
atom at dH 4.82 (1H, d, J ¼ 7.7 Hz, H-100), 4.62 (1H, d, J ¼ 7.7 Hz, H-10)] and C-atom signals
at dC 104.5(C-100), 103.8(C-10), 78.3(C-300), 78.0(C-30/C-50), 77.9(C-500), 75.3(C-200), 75.2(C-20),
71.5(C-400), 71.2(C-40), 62.6(C-600) and 62.5(C-60). The linkage of the two sugar moieties at
OH-C(4) and OH-C(12) were established from the HMBC correlations between dH 4.62
(1H, d, J ¼ 7.8 Hz, H-10) and dC 69.7(C-4), and between dH 4.82 (1H, d, J ¼ 7.8 Hz, H-100) and
dC 61.2(C-12). The 13C NMR spectral data combined with HSQC spectrum exhibited thirty-
two carbon signals, including two carbonyl carbons [dC 206.5(C-9), 201.0(C-1)], twelve
armomatic carbons [dC 159.0(C-16), 156.9(C-8), 148.8(C-13), 134.6(C-12a), 134.3(C-4a),
130.5(C-6), 129.6(C-8a), 128.4(C-14), 122.0(C-5), 119.0(C-15), 118.9(C-7), 116.1(C-16a)], two
anomeric carbons [dC 104.5(C-100), 103.8(C-10)], ten oxygenated methine carbons [dC
78.3(C-300), 78.0(C-30/C-50), 77.9(C-500), 75.3(C-200), 75.2(C-20), 71.5(C-400), 71.2(C-40), 69.7(C-
4), 61.2(C-12)], two oxygenated methylene carbons [dC 62.6(C-600), 62.5(C-60)], two sp3
hybridized methine carbons [dC 34.0(C-2), 33.6(C-10)] and two sp3 hybridized methylene
carbons [dC 30.2(C-3), 30.0(C-11)]. These NMR characteristics resembled those observed
for (4S)-4,8-dihydroxy-a-tetralone-4-O-b-D-glucopyranoside (Liu et al. 2004) and (4S)-
4,5,8-trihydroxy-a-tetralone-5-O-b-D-glucopyranoside (Fujimoto et al. 1998). However,
instead of a a-tetralonyl glucoside moiety in the known compounds, compound 1 had
two a-tetralonyl glucoside moieties in view of the HR-ESI-MS (m/z 735.1998). The linkage
of the two a-tetralonyl glucoside moieties at C-2 and C-9 was established from the 1H-1H
COSY correlations between dH 3.15 (1H, m, H-2) and dH 2.51 (1H, m, H-10). The HMBC cor-
relations also provided the linkage of the two a-tetralonyl glucoside moieties. The second
a-tetralonyl glucoside moiety was located at C-2 based on HMBC correlation between H-
10/H-11b and C-2. The relative configuration of compound 1 was established by NOESY
spectrum (Figure S9). NOESY correlation between H-4 and H-9 suggested the b-orienta-
tion of H-4 and H-9. The absolute configuration of the saccharides was determined to be
D-glucose by GC analysis of chiral derivatives in the hydrolysate of this compound. As for
the absolute configuration of the chiral carton, (4S,12S)-1 determined on the basis of
negative Cotton at ca. 190-230 nm in the CD spectrum of 1 (see Figure S2) and compari-
son of its optical rotation ([a]20 D: -65 in MeOH) with that of literature (Machida
et al. 2005).
After further comprehensive analysis of its NMR spectra (see Figure S3–S8), com-
pound 1 was identified as (2R,4S,10S,12S)-2-[7-(12,13,16-trihydroxy-a-tetralonyl-13-O-
b-D-glucopyranoside)]- 4,8-dihydroxy-a-tetralone-4-O-b-D-glucopyranoside and named
Juglansditetralone A.
As a unique quinone compound, naphthaquinone is widespread in the natural
plant and showed a series of bioactivities (Lieberherr et al. 2017). Previous review
showed that the genus Juglans was rich for a-tetralone (also their glycosides) (Jin, Sun,
Li, Diao, Zhang, Cui, Son, Zhou and Li 2016). However, very few a-ditetralone were
reported from the genus (Paedhasaradhi and Hari Babu 1978). In this study, the new
compound 1 bears two a-tetralonyl glucoside moiety, which may serve as an import-
ant structural characteristic. It might be used to distinguish Juglandaceae from other
genus, and is also rich in quinone.
Compound 6 was first isolated from the roots of Angelicae sinensis, which belongs
to isobenzofuran. This structure was responsible for the various activities such as
increasing coronary blood flow, relaxing smooth muscle, immunostimulating,

4
A.-D. WANG ET AL.
inhibiting platelet aggregation, preventing gynecological diseases treating menstrual
disorders (Peng et al. 2008). Compound 7 was rich in Anemarrhena asphodeloides,
which was norlignan compound. This compound may have potential to be developed
as medicines for the treatment of allergies by inhibiting the activation of mast cells
(Bak et al. 2016). In our research, the fatty acid (11) was first isolated from the species,
and was also first isolated from the genus Juglans. Therefore, compounds 6, 7, 11
might serve as chemical marker from systematic opinion.
The in vitro cytotoxic activities of all compounds were shown in Table S1. The
results showed that a-ditetralonyl glucoside (1), isoflavones (2–4), sesquiterpenoids
(5–6), phenolic acid (7–10) and aliphatic acid (11–13) from the green walnut husk of
J. mandshurica were all weak cytotoxic against A549 and HeLa cell lines.
3. Experimental
3.1. General experimental procedures
The NMR spectra were measured in methanol-d4, on a Bruker ARX-400 or AV600
instrument with TMS as an internal standard. CD spectrum was tested using JASCO
pu-2080 spectrometer. IR spectra were taken on a Bruker IFS-55 infrared spectropho-
tometer with a KBr disk. Optical rotations were measured on a Peking-Elmer 241 MC
Spectropolarimeter at 20 ꢁC. ESI-MS spectra were recorded on Waters Quattro micro
API LC/MS/MS spectrometer (Waters, USA). HPLC was performed on JAI LC9103
Recycling preparative HPLC (Japan Analytical Industries, Japan) equipped with JAIGEL-
ODS-AP-P column and JAIGEL-GS310 column using a JAI refractive index detector and
a JAI UV-3702 detector with MultiChro 2000 workstation.
3.2. Plant material
The green walnut husks of J. mandshurica were collected in October 2014 at Yichun,
Heilongjiang, China, and authenticated by Engineer Wei Sun (The Traditional Chinese
Medicine, Shenyang pharmaceutical University). A voucher specimen has been depos-
ited in our laboratory (voucher No. HTQ-2014-001).
3.3. Extraction and isolation
The green walnut husk of J. mandshurica (20 kg) were extracted with 70% (v/v) aque-
ous ethanol. The 70% EtOH extract (1 kg) was successively partitioned with EtOAc and
n-BuOH. The n-BuOH soluble fraction (120 g) was subjected to silica gel chromatog-
raphy, eluting with a gradients of CH2Cl2-MeOH (1:0–0:1) to give seven fractions (Fr. A
to Fr. G). Fraction A was then subjected to HPLC with MeOH-H2O (90: 10) as eluent
and each subfraction was further purified on recycling preparation HPLC with MeOH-
H2O (90:10) to yield 9 (28.4 mg), 11 (12.6 mg), 12 (5.6 mg) and 13 (8.1 mg). Fraction B
was subjected to recycling preparation HPLC with MeOH-H2O (85:15) as eluent to
obtain compound 5 (4.8 mg), 6 (15.3 mg), 7 (5.5 mg), 8 (5.6 mg) and 10 (8.2 mg).
Fraction D was further purified to recycling preparation HPLC with MeOH-H2O (45:55)
to yield 1 (25.3 mg), 2 (12.9 mg), 3 (15.4 mg) and 4 (5.7 mg).

NATURAL PRODUCT RESEARCH
5
3.3.1. (2R,4S,10S,12S)-2-[7-(12,13,16-trihydroxy-a-tetralonyl-13-O-b-D-glucopyrano-
side)]-4,8-dihydroxy-a-tetralone-4-O-b-D-glucopyranoside (1)
White amorphous power, [a]20 D -65 (c, 0.1, MeOH); HR-ESI-MS: m/z 735.1998
[M þ Na þ H2O]þ (calcd for C32H30O18Na 735.2003). 1H NMR (600 MHz, methanol-d4) d
7.55 (1H, d, J ¼ 9.1 Hz, H-14), 7.50 (1H, d, J ¼ 7.7 Hz, H-7), 7.31 (1H, d, J¼ 7.9 Hz, H-6), 7.12
(1H, d, J ¼ 7.7 Hz, H-5), 6.89 (1H, d, J ¼ 9.1 Hz, H-15), 5.44 (1H, d, J ¼ 3.2 Hz, H-4), 5.38 (1H,
d, J ¼ 3.2 Hz, H-12), 4.82 (1H, d, J ¼ 7.7 Hz, H-100), 4.62 (1H, d, J ¼ 7.7 Hz, H-10), 3.94 (1H, dd,
J ¼ 5.0, 1.6 Hz, H-600 ), 3.92 (1H, dd, J ¼ 5.0, 1.6 Hz, H-60a), 3.75 (1H, dd, J ¼ 5.0, 1.6 Hz, H-
a
600 ), 3.94 (1H, dd, J ¼ 5.0, 1.6 Hz, H-60b), 3.55 (1H, t, J ¼ 9.2 Hz, H-200), 3.40 (1H, m, H-30),
b
3.34 (1H, m, H-40), 3.33 (1H, m, H-50), 3.32 (1H, m, H-300), 3.31 (1H, m, H-400), 3.30 (1H, m,
H-500), 3.21 (1H, m, H-20), 3.15 (1H, m, H-2), 2.57 (1H, m, H-11a), 2.51 (1H, m, H-10), 3.24
(2H, m, H-3), 2.21 (1H, m, H-11b).13C NMR (101 MHz, Methanol-d4) d 206.4(C-9), 201.0(C-1),
159.0(C-16), 156.9(C-8), 148.8(C-13), 134.6(C-12a), 134.3(C-4a), 130.5(C-6), 129.6(C-8a),
128.4(C-14), 122.0(C-5), 119.0(C-15), 118.9(C-7), 116.1(C-16a), 104.5(C-100), 103.8(C-10),
78.3(C-300), 78.0(C-30/C-50), 77.9(C-500), 75.3(C-200), 75.2(C-20), 71.5(C-400), 71.2(C-40), 69.7(C-4),
62.6(C-600), 62.5(C-60), 61.2(C-12), 34.0(C-2), 33.6(C-10), 30.2(C-3), 30.0(C-11).
3.4. Acid hydrolysis of compound 1
Compound (4 mg) was treated with 1 M HCl (4 mL) at 90 ꢁC for 2 h. Then the reaction mix-
ture was extracted with CHCl3 (3 ꢂ 5 mL). The aqueous layer was collected and the water
was evaporated under vacuum with the repeated addition of MeOH to remove the solvent
completely. The residue was redissolved in anhydrous pyridine (2 mL) and mixed with a
pyridine solution of L-cysteine methyl ester hydrochloride (2 mL). After the mixed solution
was heated at 60 ꢁC for 1 h, trimethylchlorosilane (0.5 mL) was added and the resulting
mixture was stirred at 60 ꢁC for another 30 min. Then the solution was concentrated to
dryness and taken up in water (3ꢂ 1 mL), followed by extraction with n-hexane (3 ꢂ 1mL).
The supernatant was analyzed by GC. Separations were carried out on HP-5 columns
(320 mm ꢂ 30 cm, 0.25 mm). Highly pure N2 was employed as a carrier gas (1.0mL/min),
and the FID detector operated at 280 ꢁC (column temperature 160–200 ꢁC). The retention
times of the monosaccharide derivatives were as follows: and D-glucose (14.43 min).
3.5. Cytotoxicity
Human lung cancer cells (A549) and human cervical carcinoma cancer cells (HeLa) was pro-
vided by the American Type Culture Collection (ATCC). The cells were cultured in medium
(RPMI1640 for A549 and DMEM for HeLa) supplemented with 10% heat-inactivated fetal
bovine serum (FBS) and antibiotics antimycotics (PSF; 100 units/mL penicillin G sodium,
100 mg/mL streptomycin, and 250 ng/mL amphotericin B). The cells were incubated at 37 ꢁC
and 5% CO2 in a humidified atmosphere. Etoposide (Sigma, purity > 98%) was used as a
positive control. Cell viability was determined by the sulforhodamine B (SRB) protein staining
method. Cells were seeded in 96-well plates and incubated for 24 h, and were fixed (for zero
day controls) or treated with test compounds for 72 h. All compounds were solved in DMSO
(final concentration of 0.1%[v/v]), stored at ꢃ20 ꢁC and diluted to desired concentration
(0.01, 0.1, 1, 10, 100 lM) in normal saline immediately prior to each experiment. Each

6
A.-D. WANG ET AL.
concentration was tested thrice. At least three experiments were performed. After incuba-
tion, cells were fixed with 10% trichloroacetic acid (TCA), dried and stained in 0.4% sulfo-
rhodamine B (SRB) in 1% acetic acid solution. Unbound dye was washed and stained cells
were dried and dissolved in 10 mM Tris (pH 10.0). Absorbance was measured at 515 nm and
cell proliferation was determined as follows: cell proliferation (%) ¼ (average absorbancecom-
pound – average absorbancezero day)/(average absorbancecontrol – average absorbance zero day
)
ꢂ 100%. GI50 values were calculated by non-linear regression analysis using the Table Curve
2 D software (Version 5.01, Systat Software Inc., CA).
4. Conclusion
A new a-diteralonyl glucoside (1) along with twelve known compounds were isolated
from 70% EtOH extract from the green walnut husk of J. mandshurica. Compound
1–13 showed weak cytotoxic against A549 and HeLa cell lines. In this contribution,
our findings would both enrich chemical context of genus Juglans and expand the
variety of tetralonyl glucosides.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by the general project of department of education of Liaoning
Province (grant no 201610163L13) and the Natural Science Foundation of Liaoning Province
(grant no 201602712).
ORCID
An-Dong Wang
Jian-Yu Liu
http://orcid.org/0000-0003-2281-7946
http://orcid.org/0000-0003-0714-1319
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